The invention herein described relates generally to aircraft lighting systems and, more particularly, to an aircraft lighting system employing one or more high intensity discharge lamps and the construction of such lamps.
High intensity discharge (HID) lamps offer significant advantages over other lamps conventionally used in aircraft applications, such as quartz halogen or incandescent sealed beam lamps used as utility/cargo bay lights, wing and engine scan lights, logo lights, landing lights and taxi lights. When compared with quartz halogen lamps, HID lamps provide (i) nearly twice the photometric performance at less than half the energy consumption, (ii) extended lamp life by a factor of about four, (iii) better shock resistance and (iv) less heat generation. Although HID lamps have been successfully used in automotive applications, they generally have been unsuitable for use in aircraft applications for various reasons including a requirement for a larger envelope than the existing quartz halogen or incandescent sealed beam lamps presently in use.
The present invention provides a method for replacing non-HID landing and taxi lights in an aircraft wing housing that originally was designed to contain the non-HID landing and taxi lights in side-by-side relationship. This is accomplished by installing an HID landing light, an HID taxi light and a power control device in the space originally designed to accommodate the non-HID landing and taxi lights. In a particular embodiment, the HID landing and taxi lights are installed in the space originally designed to be occupied by one of the non-HID landing lights, and the power control device is installed in the originally designed to be occupied by the other of the non-HID landing lights.
Accordingly, the invention also provides an aircraft landing and taxi light system comprising an HID landing lamp, an HID taxi lamp and HID lamp power control circuitry for the lamps, wherein the landing lamp, taxi lamp and power control circuitry are mounted in a common housing. In a particular embodiment, the power control circuitry includes a ballast, and the ballast is housed in the enclosure separate from the lamps, which lamps may each include an ignitor as a part thereof that is connected by a cable to a separately mounted ballast.
According to a further aspect of the invention, an HID lamp comprises a housing, an HID bulb supported within the housing, a lens for passage of light from the HID bulb out of the housing, a primary reflector surface disposed behind the HID bulb, and a secondary reflector surface disposed in front of the bulb for reflecting light from the bulb back through the bulb for further forward reflection from the primary reflector surface through the lens. In a particular embodiment, the primary reflector is a parabolic reflector surface and the HID bulb has an arc located at about the focal point of the primary reflector surface. The secondary reflector surface preferably is a concave spherical surface having a radius of curvature less than the focal length of the parabolic reflector, and the secondary reflector surface is integral with the lens while the primary reflector surface is integral with the housing. In addition, the lens may have a lenticular array including a plurality of cylindrical surface elements for spreading the light beam emitted by the lamp.
According to yet another aspect of the invention, an HID lamp comprises a housing, an HID bulb supported within the housing, a lens for passage of light from the HID bulb out of the housing, a reflector surface disposed behind the HID bulb, and an HID ignitor located within the housing behind the reflector surface and electrically connected to the HID bulb.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail one or more illustrative embodiments of the invention, such being indicative, however, of but one or a few of the various ways in which the principles of the invention may be employed.